Furnace for burning fine coal



March '17, 1925. I 1,530,321

OOOOOOO CK ,if/fria March 17, 1925. 1,530,321

J. POLLOCK. l

FURNACE FOR BURNING FINE COAL Eile@ Aug. 3Q, 1923 2 Sheets-Sheet 2 ya@ MK* a@ Mm- )i I d auozngzq v:1o auxiliary Patented Mar. 17, 1925.

PATENT oFF'lcE.

JAMES rorLoox, or NEW Yonx, vu. Y.

1/ FUR/NACE FOR BURNING FINE COAL.

appui-,aannam Augusto, 1923. serial No. 660,191.

To all whom it may concern. v

Be it known that I, JAMES PoLLooK, a citizen of the United States, residing at New York, in the county of New York and State 5 of New York, have invented certain new anduseful Improvements in Furnaces. for Burning Fine Coal, of whic the following 1s a specification. v

This invention relates to a furnace for burning coal dust. In the anthracite coal regions of Pennsylvania large deposits of ine coal, practically dust, have accumulated, by washings from the coal dumps, the fine `particles of coal being carried by water to places where obstructions or dams have been built to allow the coal dirt, as it is called, to settle and prevent it from iowing on to adjacent lands. This coal dirt or dust is too fine for burning in a grate and I have therefore devised a furnace for burning the fine fuel, which furnace is so constructed that the fuel will be held in suspension in `an air current until it is consumed, when the ash will be carried out of the chamber with the hot gases. The interior of the furnace chamber enlarges from the bottom upwardly, and

the fuel and the air for holding the fuel in suspension are admitted into the lower and more contracted part of the cha be, while ainfor promoting co 'ustion and causing a circulation and intimate mixture of the fuel particles and gases is admitted to the Chambertin lregulated quantities at various points in the upperrpart of the furnace. The gradual upward enlargement of the fur-4 nace chamber provides room for the expansion of the gases and for the auxiliary air suppliedto promote combustion and circulation, without causlng such an increase in 40 ,the internal pressure as would force the unv burnt fuel out at the top of the furnace chamber. As the fuel is very fine, a low air pressure will keep it infsuspension, and by regulating the pressures and the quantities of air` admitted, apractically perfect combustion of the fuel may be obtained.

In the -accompanying drawing, Fig. 1 is a side elevation of the partly in vertical section; l f Fig. 2 is a top plan view of the same;

Fig. 3 shows, in central vertical section, a modified arrangement of the air connections for blowing fuel into the furnace chamber; an

furnace,

upwardly through the pipe Fig. 4 is. a detail view showing one of the slgllit openmgs.

-eferring to Fi A represents the urnace comprising an upright wall, circular in cross section and of approximately increasing diameter from the bottom to the top thereof. As shown, the wall is composed of tapering sections 1, 2, 3, and 4, and these sections are preferably made of fire clay, although they may be of metal lined with firebrick. Tubes 5, also preferably of fire clay, extend through the wall of the furnace near its lower end and at opposite sides thereof, and in these tubes are arranged burners 6, for igniting the fuel, These burners may be of any suitable kind for burning liquid fuel or gas.

The interior face of the furnace chamber w converges at the bottom to a central opening 7 in the section 1, forming a funnel d. A plate 8 fits against the bottom section and is provided with an opening 9, registering ywith the opening 7. A short tube 10 fits closely within the opening connected to the main air pipe 11 through a casing 12, which 1s in the form of an enlarged coupling.

The pipe 11 is connected to a suitable blower, not shown, for blowing air into the furnace chamber. A pipe 13 extends into the casing 12, and upon the end of this pipe, within the casing is mounted a `T fitting 14, having in one end a plug 15, which is provided with numerous small perforations, and from the other end-of the fitting a tube 16 extends upward centrally in the tube or pipe section 10, and upon thev upper -end of the tube 16 is arranged a conical nozzle 17. The base of the nozzle 17 is arranged s. 1 and 2 of the drawing, i

9 and this tube is within the tube 10 and spaced from its-finner wall, leaving a narrow annular air passageway 18 between the nozzle and the tube. With the arrangement described, air flowing from the pipe 11 into the casing 12 will ow through the perforated plug 15 into the fittin 14 and from 19 1n the nozzle into the furnace chamber, and the air will also iiow from the casing 12 or tube 10 and through the annular passageway 18 into the furnace chamber. A blow-off pipe 20 leads downwardly from the bottom of the casing 12 and this pipe is provided with a valve 23, which is normally closed. t

The pipe 13 is a feed pipe for conveying thence through the opening coal dust from a suitable hopper 24 to the interior of the fitting 14. A suitably driven worm 25 is provided in the pipe 13, for conveying a continuous supply of coal dust to the fitting 14.

The coal dust, constantly fed into the fitting 14, is carried into the furnace chamber by the air which blows through the perforations 15 into -the fitting, and thence through the opening 19 in the nozzle 17. This dust is held in suspension in the furnace chamber by the air blown through the nozzle and also through the annular opening 18, the air pressure being suitably regulated for that purpose. In starting the furnace, the burners 6 are ignited and kept burning until the furnace chamber becomes very hot and ther'fuel and gas within the chamber are ignited and in an incandescent state, when the burners may be cut off. In order to supply additional air to the burning fuel and to cause an intimate association of the coal dust entering the chamber with that which has become heated or ignited within the chamber, I construct the chamber so that it enlarges from the bottom upwardly and provide aA plurality of air inlets at various points from the bottom to the top of the furnace, these 'inlets being arranged so that the air will enter the furnace chamber at an angle to its radius and cause a constant swirling motion of the dust and gases. Thus, a feed pipe 26 leads upwardly from the main air supply pipe 11 and at the height of the section 2 of thefurnace, pipes 27 and 28 lead off from the pipe 26. The pipe 27 has branches 27a and 27h which extend intoopenings 27c inl the wall of the furnace, these openings extentiing horizontally at an angle to the axis of the chamber and being arranged approximately 90 apart. The pipe 28 has branches 28a and 28b which enter openings 28in the wall of the furnace, these openings being 90"A apart and also being 90 removed from the openings 27C. Above the pipes 27 and 28 are other pipes, 29 and 30, leading from the feed pipe 26, and above the pipes 29 and 30 are other pipes 31 and 32, which also lead from the feed pipe 26. The pipe 29 has branches 29a and 29b which lead into openings 29 in the furnace wall, tand the pipe 30 has branches 30a and 30b whichlead into similar openings 30 in the furnace wall. The pipe 31 has branches 31a and 31b which lead into openings 31c in the wall, and the pipe 32 has branches 32a and 32b which lead into openings 32c in the furnace wall. These openings, 27c and 32c are all arranged for admitting air laterally into the furnace chamber at an angle to the radius thereof and they are spaced apart circularly and also vertically of the chamber to give an even distribution of the air. The air delivered into the furnace throughI these openings causes a circulation of the air, gases and fuel in the chamber and an intimate mixture of the incoming fuel with the ignited gases and incandescent particles of unconsumed fuel. Ihe furnace chamber is made of relatively small diameter at the bottom so that the vertical column of air will be confined and will have a proper lifting force tol carry the coal dust upwardly in-to the upper part of the chamber. In the part of the chamber above the bottom section where combustion principally takes place, the chamber widens to give more space for the gases and for the air which is admitted through the branch feed pipes to promote combustion of thegases.

IVith proper regulation of the fuel fee-d and the air pressure, the coal dust will bc held in suspension in the furnace until consumed, and the ash, which is impalpable dust, will be carried out at the ton of the furnace by the draft and will deposit at some point outside of the furnace chamber. The dotted lines 33 in Fig. 1, indicate a dcfiector or crown sheet for directing the hot gases laterally through or beneath a boiler where the furnace is associated with a boiler.

Any particles of fuel, or incombustible material in the fuel, which may drop to the bottom of the furnace chamber after being injected into said furnace chamber will be carried by the funnel-shaped end a of the chamber to the annular orifice 18 where it will meet a strong jet of rir and be carried upward again int-o the chamber. If such particles are of coal they will be'consumed, and if they are of slate or stone they will eventually be disintegrated by the heat and carried out of the furnace with the gases. If any fuel accumulates in the casing 12 and it is desired to clean this casing, it is only necessary to open the valve 23 when the fuel will be blown out through the pipe 20 by air admitted from the pipe 11.

Valves c: are provided in the main pipe, the feed pipe and the various branch pipes for controlling the air pressure and flow, and at the outer end of each of the inlet pipes 27a, 27", 28a, 28", etc. is arranged a sight opening S, closed by glass or other transparent material, g, (Fig. 4) through which the condition of the fuel can be observed. These sight openings are conveniently arranged in the pipe iittmgs t and 15.

In Fig. 1 of the drawing, the air from the pipe 11 is blown through the annular orifice 18 into the furnace chamberyand air at the' same pressure passes into the nozzle for blowing the coal dust into the furnace chamber. It may be desirable to use air at one pressure for blowing the coal dust into theA furnace, and at another pressure for assistlng in holding the dust 111 suspension, and

for this purpose the modification shown in Fig. 3 may be used. In this figure, the pipe a leads upwardly through the bottom of the casing 12 and into a fitting 14a. In the upper end of the pipe 203L is a perforated plug 15a, upon which fuel from the pipe 13 may deposit. Air at suitable pressure is delivered into the pipe 20a through a pipe 11, and it will be seen that the air pressure will blow the fuel upwardly through the nozzle into the furnace chamber. Air from the pipe 11 flows directly through the opening 18 into the furnace chamber, and the pressure of the air may be different from that in the pipe 11a.

It is believed the invention will be clear from the foregoing without further description. By the arrangement described, with said chamber, and means for injecting air proper regulation of the air pressures, fine fuel may be held in suspension until completely consumed. Thus the maximum amount of heat may be obtained from the fuel. The sight-openings at the various air inlets enable the operator to observe the condition of the fuel at various heights in the furnace and enable him to determine whether the air pressure is suitable or"' whether it should be increased or diminished.

What I claim is: l

1. In a furnace for burning fine coal, a vertically arranged combustion chamber, of 'increasing diameter from the bottom toward the top, means for .blowing the coal upwardly into said` chamber, means for igniting the coal, and means forla injecting` air into the chamber above the inletfor the fuel;J

2. In afurnace for burning fine coal, a verticallyarranged combustion chamber, of increasing diameter from the bottom toward the top, means for blowing the coal upwardly into said chamber, and meansfor injecting air into the chamber above the ine let for the fuel at various points spaced verticallv apart.

3. In a furnace for burning line coal, a vertically arranged combustion chamber,

Ycircular in cross section and of increasing` diameter from the bottom toward the top, means for blowing the coal upwardly in .laterally-into the chamber above the inlet of the fuel.

4. In a furnace for burning fine coal', a vertically arranged combustion chamber,

, circular in cross section and of increasing 4diameter from the bottom toward the top,

means for blowing the coal upwardly in said chamber, and meansfor injecting air laterally into the chamber at vario-us points spaced circumferentially. and. vertically apart. L

5. In a furnace for burning fine coal, a vertically arranged combustion chamber of vertically arranged combustioncchamber of increasing diameter from the bottom toward the"-top,. a nozzle projecting upwardly 'in the lower part of said chamber, means fox` feeding line fuel to said nozzle, ,means for blowing air through said nozzle to force the fuel into the chamber, and means for forcing air into the chamber at various points above the nozzle. l

7. In a lfurnace for burning fine coal, a vertically arranged combustion chamber of circular cross section and of increasing diameter from the bottom toward the top, the bottom-of said chamber having a ceutral opening. and the side wall of the chamber converging to said4 opening, a fuel nozzle projecting .upwardly into the chamber. through said opening and spaced from `the wall of the opening to provide an annular orifice therebetween, means for feeding fine coal to said nozzle, and means for forcing' air through the nozzle and throu h said orifice .to inject' the fuel into the ciamber and hold it in suspension therein.

v8. In a" furnace for burning fine coal. a'

vertically arranged combustion chamber of circular cross-section and ofA increasing diameter from the bottom toward the top, the bottom of said chamber having a central opening. and the side wall of the chamber converging to said opening, a fuel nozzle projecting upwardly` into the chamber through said opening and spaced from the wall. of-the opening to providean annular orifice therebetween, means for feeding tine ioo coal to said nozzle. means for forcing air through the nozzleand through said orifice to inject the fuel into the chamber and vhold it in suspension therein. and4 means for forcing air laterally into the upper portions of the chamber.

9. In a furnace for burning fine coal, a vertically arranged combustion chamber, an upwardly` directed nozzlefin the lower part of said chamber, means forl blowing the coal' through said nozzle into the chamber, an air4 pipe surrounding the nozzle and spaced .therefrom tQ form an annular air opening,

means for blowing air` through said annular opening to hold the coal in suspension, and means for igniting the coal.

In testimony whereof'I hereunto affixl my signature.

JAMES PoLLooK. 

